Livelife 1 - Nephila edulis

As a counterpoint to the deadlife that usually populates this blog, I'll be posting some images of livelife that has occasionally interrupted the search for said deadlife.

Nephila edulis, or the golden orb weaver, (click image to enlarge) is common throughout the Flinders Ranges, and is an FBS, where the B and S stand for Big Spider. This one is about 15 cms (around 6 inches) in total length. The female always builds the web, as the males generally live on the periphery of her web and are usually about 1 cm (0.5 inch) long. She will sit in the centre, next to her tube of spoils, maintaining contact with the web, ready to pounce on anything unlucky enough to get trapped, and bring it back to her tube of spoils.

As befits a FBS, she builds a FBW where the B and W stand for Big Web. The central web is 120+ cm (4+ ft) long, and usually stretches across a clearing between two large bushes. In other words right across where you would normally walk. In other words right across where you would normally walk while looking down at the ground (because you are a geologist and the ground is where the rocks are).

If you are lucky, the centre of the web is at chest height, or above head height.

If you are lucky.

You aren't always lucky.

However, the local name for them is "drop-off spider" because, if you are unfortunate enough to encounter a web, the spider will generally drop off the web, or you, rather than bite (they have small jaws anyway and on the rare occasion that they bite, the results are not too bad).

Very polite of them considering the amount of work that went into the structure you have just destroyed.

The web framework is incredibly strong and will actually resist breaking, so you are in no doubt that you have just encountered one.

The World's Oldest Poo

You can learn a lot from poo.

Fossil poo, or coprolites, can provide valuable information on the size and feeding habits of the organism that produced them.

Large Cambrian coprolites are rare, and tend to be circular, but one found in the Lower Cambrian Emu Bay Shale was different.

Before going further, you should look at this short TV story that was done last year. It puts the poo in context, and the poo has a small cameo.

Keeping with the theme of using black and white photography to show critical features that may not be apparent in colour (in Palaeoporn 12), I have a black and white image of the poo. But before that I need to show you some features of Redlichia highlighted in the following image (click to enlarge).


Now pay attention as there'll be a test later. The left hand image shows a complete Redlichia. The feature in the blue box is a thorasic spine. Redlichia had a number of these attached to a number of axial rings, which comprises the central ridge. The central image shows a close up of the tip of the segment in the yellow box, showing the tip of a depression in the segment, or pluron, called the plural furrow. The right hand image shows the head region of a large Redlichia. Around the whole of the outer margin of the head is a thick zone with terrace ridges (in the red boxes) that are common in Redlichia. (Incidentally the structure coming off the head at one of the red boxes, is an antenna).

Ok, now for the image of the poo (click to enlarge).

The lower image has been augmented to delineate the poo and to highlight certain features.

Firstly the size. it's 43 mm in length and has a maximum width of 28 mm. It is formed of two 'layers' an upper diffuse layer, probably representing a fluid phase that has expanded outward. The lower layer is coarse particulate layer is crammed with trilobite fragments. If you compare the boxed areas of the poo with the three part image above (colour coded for your convenience), you should be able to make out just which parts of the ex-trilobite are represented here. The whole of the lower part of the poo is trilobite hash!

The poo tells us what was being eaten. The thorasic spine, plural tips and terrace lines present identify the remains as that of a Redlichia.

The poo tells us the size of what was being eaten - about 4 cm in length.

The poo tells us how it was being eaten. The fragments are broken. They are not crushed. They are not nibbled. They are not gnawed. They are not bitten. This means that the trilobite was broken up and not bitten (see CSI-Cambrian).

The poo tells us the size of what was doing the eating. Assuming the trilobite hash layer represents the true original thickness of the poo is 15 mm. This gives us a terminal alimentary tract of 15 mm, which roughly correlates with a 75 cm body size (from measurements done of other Cambrian fossils).

The poo tells us what was doing the eating. The broken up fragments and the size of the organism suggests Anomalocaris was the perpetrator.

So this one specimen tell us that two particular species were present, which was the predator, which the prey, and the method of predation.

Not bad for a piece of crap!

Religious Ghoul - Down Under Version

Meet Cardinal Pell, leader of the Catholic church in Australia, Religious Ghoul, and lier for Christ Ratzinger. This guy puts the "sick" into sycophant.

Pell has designs on a cushy Vatican position in Ratzinger's brave new world, and so, while all sane people were pulling their heads in and hoping Ratzinger's demonstrated lying about condoms would fade away, up steps Pell to defend the lies with some of his own.

The idea that you can solve a great spiritual and health crisis like AIDS with a few mechanical contraptions like condoms is ridiculous says Pell.

Of course it's ridiculous. The lie here is in pretending that people are advocating the position that condoms can solve the AIDS crisis. No-one, anywhere, is suggesting that condoms alone can solve the crisis. Condoms are an essential part of an integrated approach which includes health and social initiatives.

Pell knows this, but, following Ratsinger's lead, lies to people about it.

Then, to make matters worse, he quotes an unnamed health worker who, Pell claims, told him condoms were not an effective solution to Africa's AIDS problem.

He made the point that the people in remote areas are too poor to afford condoms and the ones that are available are often of very poor quality and weren't used effectively

The health worker is saying that condoms are ineffective in remote areas because they are unavailable, or the ones that are available are of poor quality. Notice the health worker does not say that condoms are ineffective, but it is their unavailability that is making them ineffective.

To any sane, rational person, the solution would be to improve the availability of condoms. But to the fevered and twisted mind of a Ratzinger sycophant, the solution, Pell's Solution, is to remove all condoms.

Lets take Pell's Solution to it's logical conclusion shall we?

Let's see, in Dafur, people are starving through a lack of food, or having sub-standard food. The Pell Solution - remove all food aid!

In Zimbabwe, people are dying through a lack of water, or water contaminated by cholera. The Pell Solution - remove all water!

Pell then deliverers his coup de grace:

If you look at the Philippines you'll see the incidence of AIDS is much lower than it is in Thailand which is awash with condoms

However, the situation is not as simple as Pell would have you think (surprised?)

There appears to be a number of factors at play here, including, a low ratio of customers to sex workers, low rates of certain other sexually transmitted diseases, and limited intravenous drug use.

Indeed as the World Health Organization representative for the Philippines has said.

I think it's a number of different factors adding up. I think they are lucky, but that's not at all the way to control AIDS.

Pell ends with another lie:

There are condoms everywhere and the rate of infection is enormous.

“That's what the Pope is talking about.

Lets, see, what did Ratzinger say again?

[AIDS] was a tragedy that cannot be overcome by money alone, that cannot be overcome through the distribution of condoms, which can even increase the problem.

No Pell, Ratzinger said condoms make AIDS worse. He lied, and you are lying now.

Cardinal Pell - lier, sycophant, Religious Ghoul. Should fit in just nicely with Ratzinger's brave new world.

Palaeoporn 12

This time Palaeoporn goes monochromatic!

Naraoia (above, scale = 1 cm) has featured here before (what? . . . I know it's not monochromatic, just wait), but this time I’m going to show what a little black and white photography can do (see!).

First of all, this (right) is what Naraoia looked like in the flesh. It had two ‘shields’ an anterior, or head shield, and a posterior shield. These shields overlapped, so that the posterior end of the head shield rested over the anterior edge of the posterior shield.

Underneath the shields, the body looked very much like that of trilobites, to whom they are closely related. In other words they had a many segmented body (including the head), and a pair of biramous appendages on most segments.

Fossils from the Lower Cambrian Emu Bay Shale are not exceptionally well preserved when it comes to fine structure. The fossils have been recrystallised into hulking great fibrous calcite crystals during a subsequent tectonic event. But, they do look good in colour, even the one above which is not a particularly good specimen.

However, occasionally you can get some detailed information, and then the best documentation is obtained using black and white photography, which is why this is still the preferred medium for journals, especially where structure is indistinct and a bugger to document!

All the photography here was done the old fashioned way, before that new-fangled digitally enhancement, with honest to goodness film, and dark rooms, and the inhalation of toxic chemicals during development and printing, Didn't effect me though, but I digress . . . err, who am I again?

Basically light and shade can show up very fine structures that colour cannot. Maybe because we can interpret subtle changes in greyscale as meaningful structures, whereas this is more difficult in colour, I don’t know. But by varying the intensity and the angle of the light, and by using high magnification and very slow film (in this case Ilford 100 and Ilford Pan F Plus) structures can be seen that are either absent of very difficult to see in colour photos.

Below I’ll show a couple of examples of what I mean.


Here is a black and white image of another specimen of Naraoia (click to enlarge). This time you can see some structure. The image on the right has been augmented to show them. Other than that the image has not been manipulated, and the structures are seen because the angle of the light hitting the specimen is very low.

A number of structures in the head can be seen, including the antennae, legs and a remnant of the hypostome, which is a rigid plate that sat directly in front of the mouth. A very thick doublure is also present. This is where the posterior shield has folded back on itself around the margin. This strengthens the shield.

The area where the two shields overlap can also be seen. Now this image is a scan of a negative that has been converted to a JPEG file and then uploaded, so some detail has been lost, but they are there . . . trust me, I’m a doctor!

Still not convinced? OK, how about this:


This image is a magnification of the last (click to magnify further), but with a slight change in the light intensity, and the angle. Other than that, and the augmentation of the right hand image, there has been no manipulation. The field of view is approximately 1 cm by 1.5 cms. Despite the fact that the magnification resulted in a very small depth of field, a number of structures are visible, in fact more so that in the last image.

There are at least 6 head appendages behind the antennae (at a push), and the hypostome is visible. Also, the margins of the anterior and posterior shields are there.

There is also a lot of wrinkling. This is because, in life, the critter was quite domed, and that has been flattened out leaving the mass of wrinkles at the front of the head. Also the left hand margin of the posterior shield is twisted near its anterior margin, and a number of major wrinkles have formed on the posterior shield in response to this twist.

If you can't document your structures, you can't publish them. Which is fine if you are dealing with Burgess Shale levels of preservation. However, the rest of us have to rely of long hours in the photography suite playing with magnification, light intensity, and lighting angles. That's before you get to the developing and printing phase.

Mmmmm . . . developing fluid . . .

Dwarf's return

Today's the day when the boys from the Dwarf are back.

At 9 pm on Dave for the next three nights, and all three episodes, plus a making-of documentary on Monday night.

Hmm . . . something nasty appears to have happened to Kochanski . . .

Show us some leg

Now that I have your attention, I'd like to talk legs. No, not the Blahnik-clad ones opposite (a homage to the Goddess), but arthropod legs (sorry).

When I talked about the new reconstruction of the anomalocarid Hurdia from the Burgess Shale, I mentioned how it supported a particular interpretation of the evolution of the arthropod limb. Now I'd like to go into a bit more detail on this because it raises some interesting questions about what was going on down in the Cambrian, especially concerning arthropods.

Now the first thing to remember, is that in the Cambrian there were lots of almost-arthropod groups scurrying around and messing up a nice, neat, columbiformes-holed phylogenetic classification, in which arthropods were real arthropods, and ancestral and derived features knew their place. Biology is messy, especially in the Cambrian, deal with it.

Basically there were two groups - the Euarthropods, and everyone else. The Euarthropods are what we would consider to be the 'true' arthropods, with all the features we have decided can be used to classify them as arthopods (except where they have been secondarily lost, for what were probably very good reasons at the time) (we could go into symplesiomorphies, apomorphies, and all the other morphies, but frankly, that way lies madness, otherwise known as cladistics).

The groups outside the Euarthropods, such as the Megacheria, the Radiodonia, can either be considered as extremely interesting groups in their own right, with many of the features of 'true' arthropods, and have much to tell us about evolution in general, and arthropod evolution in particular - or as pathetic arthropod wannabes. Almost-arthropods that failed to make the grade.

My position is, I think, clear, Anomalocaris RULES.

Anyhow, back to legs (no, not the Blahniks - concentrate). Your bog standard arthropod leg is biramous. This means that it has two main components, the walking leg (the endopodite) and the frilly bit, which is the gill (the exopodite). (see diagram at right).

As a side bar, do not underestimate the power of the gill. Confining the oxygen gathering function to a specific anatomical feature freed up the rest of the body which would have otherwise been involved in the passive adsorption of oxygen. This allowed it to be covered with calcium carbonate, producing hard outer coverings with a much greater preservation potential. The fossil trilobites you see are as much the result of gills as they are of a calcium carbonate overcoat.

It was thought that the biramous limb is an ancestral condition, and was formed by the fusion of a separate walking limb with a frilly bit. So when we look at the other groups in the Cambrian what we see are separate limbs. Hurdia is a good example. The image at right is the gill structure found in Hurdia. A nice big gill-like structure, but no walking limbs. So Hurdia supports the idea that in groups ancestral to Euarthropods, the walking limb and gill were separate structures. All well and good.

However, work by Wolff and Scholtz¹ has thrown some doubt on this neat idea.

They looked at the formation of both biramous and uniramous limbs in the crustacean Orchestia, which has both types.

They found that the biramous limb was formed by a secondary subdivision of the growth zone of the main limb axis to produce the endopodite and exopodite. But, the uniramous limb was not formed by the loss of the exopodite but by suppression of the split into exopod and endopod.

They argue that, if the biramous limb was formed by fusing two separate structures, the subsequent production of a uniramous limb would occur through the loss the exopodite. Whereas here, the exopodite never forms, and so the production of the euarthropod biramous limb is through splitting of the main limb axis during development, and not by the fusion of two separate structures.

Thus, the euarthropod biramous limb has developed from within the euarthropods, rather than be an ancestral feature.

The fossil record supports separate limbs for the pre-euarthropods, and I don't think the fusion theory is completely discredited yet. It could be that the fusion of both structures has linked their development to a large extent. But the findings are really interesting, and shows that we are still learning about early evolution during the Cambrian.

Biology! It's messy. It's complex. It's a harsh mistress. It's a scientific discipline in Blahnik boots.

¹Carsten Wolff and Gerhard Scholtz (2008) The clonal composition of biramous and uniramous arthropod limbs. Proceedings of the Royal Society, B. pp 1-6. doi:10.1098/rspb.2007.1327

Housekeeping

OK, there haven't been too many posts recently, because I've been busy (life interrupts blogging - shock horror!). But hopefully I'll have some more time over the next few weeks to get back to some geoblogging. I've got a fossilising muscle tissue recipe simmering and should be ready soon, and another Palaeoporn is due.

As I've just been touched by the immaculately attired foot of the goddess, I'd better start with the blogging to be worthy. However, at the moment I am enjoying a rather nice Penfolds Bin 138 Old Vine Grenache Shiraz Mourvedre 2002. With friends, but they are watching TV and I have control of the decanter.

I would just note that Pharyngula had 2,296,911 visits in March, whereas Sandwalk had 107,747 over the same period. Evolving Thoughts had 71,434 (if the average per day can be believed). And me? Well I had, . . . umm . . . aah . . . never mind.